A transparent display using OLEDs can be devided into a display region and a penetrative region according to pixels of the display. The display region is disposed with a pixel structure and actually emits light. Since the penetrative region has nothing inside, the back of the display can be seen through a transparent substrate. In a pixel, the penetrative region can overlap the display region, be abreast of the display region, or be among mono-chromatic LEDs. Because the area of the active luminous region is smaller than that of the non-transparent region, the transparent display usually has a lower brightness and a lower contrast of the background.